Parts conveyor

ABSTRACT

The invention is a conveyor for picking up parts from a supply station and transferring them to a parts delivering station or point of use. The conveyor comprises a pivotally mounted arm with pulleys supporting a cable from which depends a permanent magnet parts holder. Winch means comprising a motor and a reel connected to the cable are used to raise and lower the parts holder, and the cable and arm are so connected that winding and unwinding of the cable effects pivotal movement of the arm between the parts supply station and the parts delivering station.

United States Patent 1 Klapes et al.

[54] PARTS CONVEYOR [75] Inventors: Michael C. Klapes, Lynnfield;Herbert N. MacRae, Beverly, both of Mass.

[73] Assignee: Delta Engineering Winchester, Mass.

[22] Filed: Aug. 5, 1971 [21] Appl. No.: 169,354

Corporation,

[52] U.S. Cl. ..2l4/l7 C, 212/40, 212/66, 214/1 BH, 214/658, 294/655[51] Int. Cl ..B66c 23/84 [58] Field of Search ..2l4/1BC,1BH,17 C, 151,214/309, 658; 294/655; 212/40, 66

[56] References Cited UNITED STATES PATENTS 10/1952 Fischer.. ..294/65.52/1956 Ruppe ..294/65.5X

[451 Jan. 9, 1973 Primary Examiner-Robert G. Sheridan Attorney-Robert J.Schiller et al.

[57] ABSTRACT The invention is a conveyor for picking up parts from asupply station and transferring them to a parts delivering station orpoint of use. The conveyor comprises a pivotally mounted arm withpulleys supporting a cable from which depends apermanent magnet partsholder. Winch means comprising a motor and a reel connectedto the cableare used to raise and lower the parts holder, and the cable and arm areso connected that winding and unwinding of the cable effects pivotalmovement of the arm between the parts supply station and the partsdelivering station.

11- Claims, 7 Drawing Figures PAIENIEDJMI 9197a SHEET 1 [IF 3 FIG.

INVENTORQ MICHAEL C. KLAPES BY STAI/ZI' 7 panz l' cio ATTORNEYSPARTSCONVEYOR This invention relates to conveyor apparatus and moreparticularly to a magnetic loading conveyor.

In many industries it is desirable to employ conveyor means fortransporting parts to assembly equipment, processing apparatus, feedingequipment, packaging machines, and the like. Typically, to reduce laborcosts and eliminate worker fatigue, it is desirable to employ a conveyorfor lifting parts from a supply container to a parts feeder such as avibrating bowl feeder. Essential requirements of such conveyor equipmentare reliability, relatively low cost, and automatic operation.l-Ieretofore there has been available conveying equipment for suchpurposes which employs either an electromagnet or a permanent magnet forlifting and conveying ferrous and other magnetic parts. However,electromagnetic conveyors suffer from a number of limitations, notably,relatively high cost. Permanent magnet conveyors heretofore availablehave been limited by relatively high cost, fixed limits of operation,excessive conveyor size to capacity ratio, and design considerationswhich limit potential uses of the equipment.

The primary object of this invention is to provide a new permanentmagnet conveyor for lifting and transferring magnetic parts to bowlfeeders, packaging equipment and the like which is adapted to be addedto or used in conjunction with existing manufacturing equipment such asbowl feeders, packaging machines, etc., is a self-contained unit thatmay be shipped completely assembled and is characterized by simplicityof design, relatively low manufacturing cost and reliability ofoperation.

A further object of the invention is to provide a new magnetic conveyorfor loading parts into a machine which occupies relatively little space,can operate repetitively through complete cycles, is adapted to becontrolled automatically according to demand, and embodies a basicdesign such that it can be manufactured in various sizes.

Still a further object of the invention is to provide a conveyor of thetype that employs a permanent magnet for lifting parts which ischaracterized by a height compensating feature which permits supplycontainers to be placed at floor level or to be stacked, with changeoverfrom one supply container to another being effected in a matter ofseconds.

The foregoing and other objects of the invention described in orrendered obvious by the following detailed specification are achieved byproviding a conveyor which essentially comprises a conveyor arm, meanspivotally supporting the conveyor arm for swinging movement in ahorizontal plane, a flexible cord or cable having a permanent magnetparts-loading assembly connected to one end, means mounting the cable tothe conveyor arm and the support for said arm so that swinging movementof said arm causes swinging movement of said magnetic assembly, andmeans for winding and unwinding the cord so as to raise and lower theheight of the magnet assembly. The cable is arranged so that it exerts aforce on the conveyor arm which urges the conveyor arm in a firstdirection about its pivot point. Additional biasing means are providedfor urging the conveyor arm to move in a second opposite direction aboutits pivot point. The means mounting the cord and the conveyor arm arealso arranged so that, depending upon the position of the conveyor andthe extent to which the cord has been wound or unwound, the conveyor armwill either move relative to its pivot point or will remain stationaryas the cord is being wound or unwound. The permanent magnetparts-loading assembly is adapted to pick up parts magnetically and todischarge them when the tension on the cord exceeds a predeterminedlimit.

Other features of the apparatus are described in the followingspecification which is to be considered together with the accompanyingdrawings wherein:

FIG. 1 is a front elevational view partly in section of a conveyorconstructed in accordance with the present invention mounted on amachine having a vibrating bowl feeder;

FIG. 2 is a side elevational view, partly in section, of the sameapparatus with the conveyor arm at about the midpoint of its swing;

FIG. 3 is a plan view of the same conveyor on a reduced scale;

FIG. 4A is a sectional view in elevation of the front end of theconveyor arm'and the permanent magnet parts holder;

FIG. 4B is a view similar to FIG. 4 but with the permanent magnet of theparts holder in parts-releasing position;

FIG. 5 is a fragmentary sectional view in elevation showing how the armis pivotally supported; and

FIG. 6 is a schematic view of the electrical control circuit of theconveyor.

A conveyor constructed in accordance with the present invention isdesigned to lift parts of ferrous and other magnetic materials from oneplace and deposit them in another place. A primary field of the use isin removing parts from a storage bin or shipping container anddepositing the same in a hopper or feeder mechanism associated with someform of production equipment. Referring now to FIG. 1, the illustratedconveyor apparatus is associated with a machine, a portion of which isshown at 2 which is supplied with parts from a bowl feeder 4 that ismounted on a vibrator 6. By way of example, the machine 2 may be anarticle counting machine of the type illustrated and described in US.Pat. No. 3,573,477 of Michael C. Klapes, issued Apr. 6, 1971 forRADIATION SENSITIVE AP- PARATUS FGR DETECTING CONVEYED ARTI- CLES.

The conveyor comprises a hollow column 10 which is mounted on themachine 2 or alternatively may be mounted on a stand or other supportwhich is separate from the machine 2. The column 10 supports arectangular enclosure 12 containing elements hereinafter described andalso an arm 14 which in the illustrated embodiment is constructed of aUshaped channel member having side walls 16 and 18 and a horizontalconnecting wall 20. The enclosure 12 comprises a rear wall 22 and topand bottom walls 24 and 26. The side and front of the enclosure 12 areformed with large apertures 28 and 30 (see FIGS. 1 and 2) which permitaccess to thecomponents contained within the enclosure 12 and which arenormally covered by removable cover panels (not shown).

The arm 14 may be pivotally connected to the column 10 in a variety ofways known to persons skilled in the art. One suitable mode ofconnecting the arm 14 to the column is shown in FIG. 5. The column 10extends through suitable aligned openings in the top and bottom walls ofthe enclosure 12, and these walls are welded to column 10 so that thehousing 12 is rigidly supported by the column. Mounted within the upperend of the column 10 is a conventional roller bearing unit 32. The outerrace of the roller bearing unit 32 is secured to the column 10 while itsinner race is secured to a hollow stub shaft 34 that is mounted withinthe bearing unit. The arm 14 is provided with a cylindrical sleeve 36that is welded to the underside of its horizontal wall 20. The sleeve 36fits down over and is releasably secured to the stub shaft 34 so thatthe stub shaft and the arm 14 can rotate as a unit relative to thecolumn 10.

Referring now to FIGS. 1-3 and 5, the arm 14 is provided with arectangular opening 40 to accommodate a pulley 42 that is rotatablymounted on a horizontal pulley shaft 44 that is mounted in suitablebearing blocks (not shown) that are attached to the underside of thewall of the arm 14. As seen in FIG. 3, a second pulley 46 is rotatablymounted on a vertically extending pulley shaft 48 that is secured to thearm 14 at a point adjacent to its pivot point. A third pulley 50 isrotatably mounted on a pulley shaft 52 that is vertically mounted to asupporting plate 54 that is rigidly secured to the upper wall 24 of thehousing 12. The pulleys 42, 46 and 50 serve to guide a flexible cord orcable 56 which has one end secured to the arm 14 at a convenient pointas shown at 58. The other end of the cord 56 extends down through thehollow stub shaft 34 and into the hollow column 10. This other end ofcord 56 is attached to and supports a counter-weight 60 that is disposedwithin column 10. It is believed to be apparent that the counter-weight60 acts through the cord 56 to urge the arm 14 to pivot in acounterclockwise direction as seen in FIG. 3.

Disposed within the enclosure 12 and attached to its bottom wall 26 is aconveyor drive mechanism comprising an A.C. electric motor 64 and a gearreduction unit 66. The gear reduction unit 66 is coupled to and drivenby the output shaft of motor 64. The gear reduction unit 66 has anoutput shaft 68 on which is secured a reel 70. Connected to reel 70 is asecond flexible cable or cord 72. The opposite end of cable 72 issecured to and supports a permanent magnet parts holder identifiedgenerally by numeral 74.

As seen in FIGS. 1 and 2, the enclosure 12 contains a guide pulley 76for the cord 72. Pulley 76 is mounted on a shaft 78 which is supportedby two spaced blocks 80 and 82 that are affixed to the bottom wall 26 ofthe enclosure. The two blocks 80 and 82 have vertically extending slots83 which are elongate in a vertical direction and which have ahorizontal dimension just large enough to permit vertical movement ofthe shaft 78. Mounted on the ends of the shaft 78 are two small wheels84 and 86. Mounted adjacent to the two blocks 80 and 82 are two smallswitches LSD and LSDR having resilient spring operating fingers 88 (seeFIG. I) which extend below the wheels 84 and 86. When the shaft 78 movesdownward in the slots 83, the wheels 84 and 86 engage the fingers 88 toactuate the switches LSD and LSDR. When the shaft 78 moves upwardly inthe two slots, the wheels 84 and 86 move away from the fingers 88 so asto allow the switches to return to their normal states.

Referring now to FIGS. 1, 2, and 3, the cord 72 is guided by fouradditional pulleys 94, 96, 98 and 100. The pulley 94 is mounted on ashaft 102 that is affixed to a support block 104 that is attached to theupper side of the top wall 24 of the housing 12. The top wall of thehousing is provided with an opening through which the cord can pass frompulley 76 to pulley 94, the pulley 94 being located directly above thepulley 74 but with its shaft oriented at a right angle to shaft 78. Thepulley 96 is mounted on a shaft 106 that is vertically mounted to thetop wall 24 of the housing 12. The pulley 96 is located in line with butforwardly of the pulley 94. The pulley 98 is rotatably mounted on avertical shaft 108 which is affixed to the underside of the horizontalsection 20 of the arm 14. A side opening 109 in arm 14 permits cord 72to extend from pulley 96 to pulley 98. The pulley is rotatably mountedon a shaft 110 whose ends are affixed to the side walls 16 and 18 of thearm 14. The pulley 100 is located at the forward end of arm 14, whilethe pulley 98 is located between the pulley 100 and the midpoint of thearm 14. As a result of the relative locations of pulleys 94, 96, 98 and100, tension applied to the cord 72 as a result of a pulling forceexerted by reel 70 will cause the arm to be urged in a clockwisedirection (as seen in FIG. 3) if the magnetic parts loader 74 isrestrained from moving toward the pulley 100. If sufficient tension isexerted on cord 72, the pulling force which the cord exerts on the arm14 can offset the pulling force exerted by cord 56, with the result thatthe arm 14 can be made to swing clockwise.

Swinging movement of the arm 14 is limited to first and secondpredetermined limit positions by means of two stop assemblies 112 and114. These stop elements comprise L-shaped brackets 116 affixed to theupper side of the top wall 24 of the housing 12, and resilient bumperpads 118 which are engaged by the side walls of the arm 14. As shown inFIG. 3, the two stops 112 and 114 are spaced so as to permit the arm 14to swing through an angle of approximately 90.

Referring now to FIGS. 1, 2, 4A and 4B, the free end of arm 14 isprovided with a depending extension comprising a pair of side plates 120and 122 which are affixed to the side walls 16 and 18 of the arm. Thebottom ends of plates 120 and 122 are connected by a cross plate 124.Cross plate 124 has an aperture 126 substantially in the center. Acylindrical sleeve 128 is affixed to the upper side of the cross plate124 in coaxial relation with the aperture 126. Aperture 126 and sleeve128 are aligned with the cord 72 depending from the pulley 100. Attachedto the inside surface of side plate 120 by means of a bracket 130 aretwo identical switches LSU and LSUR (see also FIG. 6). These switchesare mounted in side-by-side relation and thus only switch LSU is visiblein FIGS. 2, 4A and 4B. These switches have resilient operating fingers132 which are connected to each other and which are provided at theirends with a rounded projection 134 which extends through a side openingin the sleeve 128.

Referring now to FIGS. 2, 4A, and 4B, the permanent magnet parts holdercomprises a closed housing 136 that is made ofa non-magnetic materialsuch as aluminum or a suitable stainless steel. Housing 136 preferablyis of generally rectangular cross section. Mounted within the housing136 is a permanent magnet 138. The permanent magnet has an elongate rodextension 140 which extends through an opening in the upper end wall ofthe housing 136 and is connected to a plug member 142. Plug member 142comprises two integral sections, one section having a frusto-conicalsurface 144 and the other section having a cylindrical surface 146. Thecylindrical section 146 is sized so as to slide snugly within the sleeve128. The cord 72 extends axially into the plugl42 through a suitablebore and is secured to a cross pin 148 that is anchored in the plug. Thefrusto-conical surface 144 facilitates entry of the plug into sleeve 128as the cord 72 is wound upon reel 70.

The magnetic parts holder 74 further includes a resilient pad 150mounted on the top side of housing 136 for engagement with the undersideof the crossplate 124 of arm 14 as shown in FIGS. 4A and 4B. Acompression coil spring 152 surrounds the rod 140, with the upper end ofthe spring bearing against the inner surface of the upper side of thehousing 136 and the bottom end of the spring bearing against thepermanent magnet 138. Spring 152 is made strong enough so that it cannotcompress except under a force greater than the force required to beexerted by cord 72 on arm 14 to overcome the force exerted by cord 56,i.e., the force required to cause the arm to pivot clockwise as viewedin FIG. 3. Accordingly, the spring 152 normally holds the magnet 138against the bottom side of the housing 136. Thus if the housing 136 islowered into engagement with a collection of parts made up of a ferrousmetal or other magnetic material, the magnetic field of the magnet 138will cause the parts to be attracted to and held against the bottom ofhousing 136. However, if the magnet 138 is drawn up away from the bottomof the housing as shown in FIG. 4B, the influence of its magnetic fieldon the parts engaging the bottom of the housing 136 will be considerablydiminished, causing the parts to fall by gravity away from the housing.It is to be appreciated that other forms of permanent magnet partsholders are known to persons skilled in the art, e.g., one of theseveral types shown in U.S. Pat. No. 2,693,979, issued Nov. 11, 1954 toG. L. Russell for MAGNETIC DEVICE, may be sub stituted for the magneticparts holder comprising housing 136 and magnet 138 illustrated in FIGS.4A and 48.

It is to be noted that when the housing 136 is pulled up againstcross-plate 124, the plug 142 enters sleeve 128 and occupies theposition shown in Fig. 4A. At this point the tapered surface 144 of theplug does not en gage the projection 134 of switches LSU and LSUR.However, when magnet 138 is pulled up in housing 136, the plug 142 movesup in sleeve 128 far enough for its cylindrical surface 146 to engagethe projection 134 and thereby force the fingers outwardly from thesleeve so as to actuate switches LSU and LSUR. These switches form partof the conveyors automatic control system.

The mode of operation of the conveyor above described and illustratedwill now be described with reference to FIG. 1. Assume that parts arerequired to be transferred to the feeder bowl 4 from a bin or a suitableshipping container, e.g., a corrugated cardboard container as shown at154 containing a supply of steel screws 156. Assume also that the arm 14is in the position shown in FIG. 3 with the magnet parts holder 74dangling from arm 14 as shown in FIG. 2. At this time some of the cord72 will be wound on the reel 70. The motor 64 is operated in a directionto cause the reel to unwind cord 72 so as to lower the magnetic partsholder 74 into the container 154. The parts holder 74 is lowered farenough to engage parts in the container 154. Accordingly, since themagnet 138 will be in the position shown in FIG. 4A, a plurality ofparts 156 will be magnetically attracted to and will adhere to thehousing 136. Thereafter the motor 64 is operated in the reversedirection so as to cause the cord 72 to be wound up on the reel 70. Asthe cord 70 is being wound, the arm 14 will remain stationary due to thefact that the pulling force exerted by cord 56 is substantially greaterthan the pulling force: exerted by the cord 72. The parts holder 74 willcontinue rising after plug 142 enters sleeve 128 until its resilient padengages the cross-plate 124 on the end of arm 14. Thereafter as the reel70 continues to wind cord 72, the parts holder 74 will be held againstthe cross-plate 124. Since the force required to compress spring 152 isgreater than that required to cause the arm 14 to pivot away from stop114, the continued winding of cord 72 will cause the arm 14 to swing ina clockwise direction until it strikes stop 112. As seen in FIG. 3, whenthe arm is against the stop 114, the cord 72 extends from pulley 96 atan angle of approximately 45 to the arm, so that the tension in the cord72 can exert a turning force on the arm 14. The angle of the cord withrespect to the arm 14 will increase as the arm 14 moves clockwise and isabout 90 when the arm strikes stop 112. Thereafter, as reel continues towind cord 72, and because housing 136 is stopped by cross plate 124 andarm 14 is stopped by stop 114, the increasing tension on the cord 72will exert sufficient pulling force on the plug 142 to compress spring152, withthe result that the magnet 138 will move upwardly in thehousing 128 far enough to release the parts 156. The conveyor ispositioned with respect to the machine 2 so that when the arm 14 hasbeen stopped by stop 112, the magnetic parts holder 74 will be directlyabove the bowl 4. Therefore, when the magnet 138 moves upwardly inhousing 138 to release the parts 156, the parts will fall directly intothe bowl 4.

Winding movement of the reel 70 is stopped as soon as the parts 156 havebeen released by part holder 74. Then motor 64 is reversed so as tocause pulley 70 to unwind cord 72. As the cord unwlnds, the operation isexactly the reverse of what has just been described. First the plug 142moves down out of the sleeve 128 and the magnet 138 moves downwardly inthe housing 128 to the position shown in FIG. 4A. Thereafter thedecreasing tension in cord 72 allows the arm 14 to be pivotedcounterclockwise under the force exerted by cord 56 until it is stoppedby stop 114. As soon as the arm 14 has stopped moving, the cord 72 willbegin to lower the magnetic parts holder 74 away from the cross-plate124 and back down into the parts container 154 to pick up more parts.

In the preferred embodiment of the invention, the conveyor is adapted tooperate automatically and repetitively through the cycle abovedescribed. Additionally, the conveyor is controlled so as to releaseparts into the bowl 4 only when the bowl 4 requires additional parts.Release of parts only on command is achieved by providing a limit switchLSH on the conveyor and by mounting a level sensor to the bowl 4. Thelimit switch LSI-I is shown in FIG. 3. It is mounted on the underside ofthe horizontal section of arm 14 and includes an operating finger 158that extends through an opening in the side wall 16 of the arm. SwitchLSH is located on arm 14 so that as arm 14 reaches the end of itsclockwise movement, the switch will be actuated by engagement of finger158 with stop 114.

Referring now to FIG. 1, the level sensor may take the form of a bracket160 attached to the bowl 4 and pivotally supporting an arm 162. Mountedon the end of arm 162 is a conventional mercury level switch LCS havingterminals which are connected by leads (not shown) to the electricalcontrol system of the conveyor which is described hereinafter. Themercury switch LCS is of the type that will close when the arm 162 isnearly or exactly vertical and will open when the arm 162 is moved to aninclined position. The arm 162 depends far enough to engage parts 156disposed in the bottom of the bowl 4. If the level of parts 156 isrelatively high, the parts will force the arm into an inclined positionso that the contacts of switch LCS will be open. As the level of theparts is depleted the arm 162 drops to a more vertical position andultimately the switch contacts close to provide a control signal to thecontrol system of the conveyor.

Referring now to FIG. 6, the control circuit includes the switcheshereinabove described plus other circuit components that areconveniently housed in a case 167 (see FIG. 1) that is mounted withinthe housing 12. The control circuit comprises a pair of bus lines L1 andL2 adapted to be connected to an AC. current source (not shown) andincluding a manually operable power switch SW1. The motor 64 is a singlephase motor having a main winding and a start winding. The main windingis connected across the bus lines via leads 168 and 170 and the normallyopen contacts SMRl of a motor starting relay SMR. The start winding ofthe motor is connected across the bus lines via a circuit arrangementdescribed below which includes switches LSD, LSU, and LSH, plus contactsof two relays CRR and CRH and the coil of relay SMR. Relay CRR controlsthe direction of operation of the motor, relay SMR controls starting andstopping of the motor, and relay CRH controls continued operation of themotor after arm 14 has swung to the limit position determined by stop112.

Switch LSD (normally closed) and contacts CRRI (normally open) and CRR2(normally closed) of relay CRR are connected in series across the buslines via the coil of relay SMR and leads 172 and 174, with the junctionof the two pairs of contacts being connected to one side of the motor'sstart winding via a lead 176. Switches LSU (normally closed) and LSD andthe contacts CRR3 (normally open) and CRR4 (normally closed) of relayCRR are connected in series across the bus lines via leads 174 and 176and the coil of relay SMR. The junction of the two pairs of contactsCRR3 and CRR4 is connected to the other side of the motors start windingvia a lead 178. Additionally, the contacts CRHI (normally open) of relayCRH are connected across switch LSI-I.

Switch LSDR (normally closed), contacts CRRS (normally open) of relayCRR, and the solenoid of relay CRR are connected in series across thebus lines via leads 180 and 182. Switch LSUR and another switch IBl(both normally open) are connected in parallel with each other acrossswitch LSDR and contacts CRRS. Switch P81 is a manually operable,pushbutton switch of the type having a spring that urges its push-buttonto open position; it is used to energize relay CRR so as to closecontacts CRRl and CRR3 and thus cause the motor to unwind cord 56.

Mercury level switch LCS and the solenoid of relay CRH are connected inseries with each other across the bus lines via leads 184 and 186.

Automatic operation of the machine under control of the circuit of FIG.6 will now be described. Assume (I) that arm 14 is in the position ofFIG. 3 with the motor 64 off and the permanent magnet parts holder inthe position of FIG. 2 over the container 154, and (2) that switch LCSis open. Switch SW1 is closed and simultaneously the operator depressespush boton switch FBI to energize relay CRR and thereby close contactsCRR], CRR3, and CRRS. Current flows to the motors starting coil throughswitch LSD, contacts CRRl and CRR3 and the relay coil SMR, causing themotor to start and to drive reel in a first direction to unwind cord 72and lower the parts holder 74. This downward movement continues untilthe parts holder 74 is impeded by its contact with parts in container154 and cord 72 has become slack enough to allow pulley 73 to drop andopen switches LSD and LSDR. Opening of switch LSD stops the motor.Opening of switch LSDR causes relay CRR to drop out so that its contactsCRRl, CRR3 reopen and contacts CRR2, CRR4 reclose. As a result, currentflows to the starting coil of the motor via switches LSH, LSU andcontacts CRR2, CRR4 so as to cause the motor to rotate in a secondopposite direction to wind cord 72 on reel 70. The permanent magnetparts holder will rise up out of the container 154 with parts 156magnetically held thereto and the increased tension on cord 72 willcause pulley 74 to move up far enough to allow switches LSD and LSDR toreclose. The arm 14 will remain stationary against stop 114 until theparts holder 74 reaches the position shown in FIG. 4A where it isstopped by engagement of its resilient pad 148 with the cross plate 114.At this point spring 150 will prevent the magnet 134 from moving awayfrom the bottom end of the housing 128 and the increasing tension incord 72 will cause the arm 124 to swing clockwise (as seen in FIG. 3)until it en gages stop 112. At the same time, switch LSH is opened.Since switch LCS is also open, (indicative of an ample supply of partsin feeder bowl 4), the solenoid of relay CRH is dcenergized and contactsCRHl are open. Accordingly, the opening of switch LSI-I interrupts thecircuit to the motor through switch LSU and contacts CRR4 and CRR2,causing the motor to stop with arm 14 held against stop 112 and theparts holder held in the position of FIG. 4A. Assuming that the machine2 is operating, parts will continue to be fed out of bowl 4 untileventually the level of parts in the bowl will be low enough to allowthe mercury switch LCS to close. When this occurs, relay CRH isenergized to close contacts CRHI thereby reestablishing current flow tothe motor through switch LSU and contacts CRR4 and CRR2. The motor thencontinues to wind cord 72 on pulley 74. Since arm 14 cannot move furtherin a clockwise direction, the resumed winding of cord 72 produces a cordtension sufficient to overcome spring 150, with the result that themagnet is pulled away from the bottoms end of housing 128 far enough(see FIG. 4B) to release the parts 156 into bowl 4. At the same time theplug 138 moves up in sleeve 118 far enough to cam switch fingers 132 ofswitches LSU and LSUR outwardly of the sleeve, with the result thatthese switches are opened and closed respectively Opening of switch LSUstops current flow to the motor through contacts CRl-ll, CRR4 and CRR2.Closing of switch LSUR causes the solenoid of relay CRR to be energized,thereby opening contacts CRR2 and CRR4 and closing contacts CRR], CRR3,and CRRS. Since switch LSDR is closed, the closing of contacts CRRSestablishes a holding circuit for relay CRR. Since switch LSD is closed,the closing of contacts CRRl and CRR3 causes current to be supplied tothe motors start coil in a direction to make the motor unwind cord 72.As the cord 72 unwinds, the following occurs: first plug 138 moves downin sleeve 118 to restore the magnet to the position of FIG. 4A and toreclose and reopen switches LSU and LSUR respectively; second, arm 14begins to swing counterclockwise and this movement allows switch LSH toreopen; third, arm 14 is stopped by stop 114; fourth, the parts holder74 drops down into container 154; fifth, the parts holder is stopped byparts in the container and, since the motor is still unwinding cord 72,the cord becomes slack; sixth, the slack in cord 72 causes pulley 72 todrop and reopen switches LSD and LSDR; seventh, opening of switch LSDstops the motor and opening of switch LSDR causes the relay CRR to dropout; and eighth, as soon as relay CRR drops out, current flow to themotor is resumed through switches LSH and LSU and contacts CRR4 andCRR2. Thereafter the machine continues to operate as above describedexcept that operation of the motor will not be interrupted when arm 14is stopped by stop 112 and switch LSH is reopened if relay CRH isenergized at that time due to there being an unsufficient supply ofparts in the bowl to cause mercury switch LCS to be closed. If thelatter switch is open, the motor will stop when switch LSH is opened andwill remain off until enough parts have been removed from the bowl tocause switch LCS to close.

It is believed to be apparent that the invention as above described andillustrated is adapted to automatically compensate for the height ofparts in the supply or storage container 54 and also permits containersto be stacked one above the other, with no need to shut down theconveyor or manually adjust any controls in order to allow the conveyorto keep operating effectively as each container in the stack is emptiedand removed to expose the parts in the next lower container. A furtheradvantage is that the conveyor can be made in various sizes andcapacities without any fundamental change in design or mode ofoperation. Furthermore, it is possible to modify the control circuit soas to permit the machine to be controlled manually. The conveyor may beused with various machines and the ability to operate only on demandafforded by mercury switch LCS may be achieved in other ways, e.g., bymeans ofa transducer adapted to weigh the contents of the supply hopperof a machine and to close a switch when the measured weight of parts inthe supply hopper falls below a predetermined minimum. It also isrecognized that a reversible d.c. electric motor may be used in place ofmotor 64.

What is claimed is:

1. A conveyor for lifting, transporting and releasing parts susceptibleof magnetic attraction comprising:

an arm;

support means pivotedly supporting said arm for swinging movement;

rotatable winding means;

a flexible cord having one end connected to said winding means so thatsaid cord may be wound or unwound by said winding means according to thedirection of rotation thereof;

reversible drive means for said winding means;

a plurality of pulleys of which at least one is mounted to said supportmeans and at least one is mounted to said arm;

a parts holder comprising a member having a surface to which said partsmay be held under the influence of a magnetic field a magnet capable oflimited movement toward and. away from said surface, and means biasingsaid magnet toward said magentic surface, and means connecting theopposite end of said cord to said magnet so that said parts aresuspended from said cord and tension on said cord opposes said biasingmeans;

a plurality of cord guiding means of which at least one is mounted tosaid support means and at least one is mounted to said arm, said cordextending from said winding means to said magnet assembly along a pathdetermined by its engagement with said cord guiding means;

stop means on said arm in position to be engaged by said parts holdermember and thereby limit movement of said member toward said arm whensaid cord is being wound by said winding means;

means for limiting swinging movement of said arm between first andsecond limit positions;

said cord guiding means being disposed so that when said cord is undertension it exerts a turning force on said arm that urges said arm towardsaid second limit position; and

arm biasing means biasing said arm toward said first limit position,said biasing means providing a turning force on said arm that exceedsthe turning force exerted by said cord when it is under tension as longas said parts holder member is disengaged from said stop means and isless than the turning force exerted by said cord when said winding meansis operating to wind said cord with said parts holder member in'engagement with said stop means;

said magnet biasing means exerting a biasing force on said magnet whichis greater than the turning force required to be exerted by said cord onsaid arm in order to overcome the force exerted by said arm biasingmeans and move said arm to said limit position, whereby said magnetcannot be pulled away from said surface by said cord until said arm hasbeen stopped in said second limit position.

2. A conveyor according to claim 1 further including:

means for operating said drive means so as to sequentially (a) unwindsaid cord until it is slack due to said parts holder being in engagementwith said parts to be lifted and transported, (b) stop unwindingandstart winding said cord, continue winding said cord so that said arm isforced to swing to said second limit position and said magnet is causedto move away from said surface after said arm has reached said secondlimit position, and (d) stop winding and start unwinding said cord so asto allow said magnet to move back to its original position with respectto said surface and thereafter allow said arm to return to said firstlimit position.

3. A conveyor according to claim 1 wherein said arm biasing meanscomprises a second cord connected to said arm, and means including acounterweight connected to said second cord for causing said second cordto urge said arm toward said first limit position.

4. A conveyor according to claim 1 wherein said drive means is areversible electric motor and said operating means comprises anelectrical circuit for controlling operation of said motor, said circuitincluding limit switch means for stopping operation of said motor andadditional switch means for reversing said motor.

5. A conveyor according to claim 4 wherein said circuit has two limitswitches and said additional switch means comprises two reversingswitches, and further including means for operating one limit and onereversing switch when said cord becomes slack and means for operatingthe other limit and reversing switches when a predetermined amount ofsaid cord has been wound by said winding means.

6. A conveyor according to claim 5 further including another limitswitch that is operated when said arm is swung to said second limitposition.

7. A conveyor according to claim 4 mounted so as to discharge parts intoa hopper, and means for controlling operation of said drive meansaccording to the supply of parts in said hopper.

8. A conveyor according to claim 7 wherein said hopper is a bowl mountedon a vibrator, and said last mentioned means comprises a parts levelsensor comprising a moveable member mounted so as to change positionaccording to the level of parts in said bowl, and a switch that opens orcloses according to the position of said moveable member.

9. A conveyor according to claim 7 wherein said hopper is part of anarticle counting machine.

10. In combination with an article counting machine having a vibratingbowl feeder, a conveyor for delivering parts to said bowl feeder, saidconveyor comprising:

an arm;

means pivotally mounting said arm for swinging movement in asubstantially horizontal plane;

a permanent magnet parts holder including a housing, a permanent magnetwithin said housing; and spring means holding said magnet close to asurface of said housing;

a reversible cord winding mechanism;

a flexible cord having one end connected to said magnet and its oppositeend connected to said winding mechanism;

means on said arm for supporting said cord so that said parts holder issuspended from said arm by said cord' I means for limiting swingingmovement of said arm between a first parts loading position and a secondparts releasing position above said bowl feeder;

biasing means for applying to said arm a turning force that urges saidarm to said first parts loading position;

cord guiding means arranged so that when said cord is under tension itapplies to said arm a turning force that urges said arm to said secondparts releasing position; and

stop means for stopping movement of said parts holder toward said armwhen said cord is being wound.

11. A conveyor according to claim 10 further including:

means for operating said winding mechanism so that said cord first liftssaid parts holder until said parts holder is stopped by said stop means,then pulls said arm to said second parts releasing position, next pullssaid magnet away from said housing surface, then allows said magnet tomove back to its original position with respect to said housing surface,next allows said arm to be pulled back to said first parts loadingposition by said biasing means, and finally relowers said parts holder.

1. A conveyor for liftinG, transporting and releasing parts susceptibleof magnetic attraction comprising: an arm; support means pivotedlysupporting said arm for swinging movement; rotatable winding means; aflexible cord having one end connected to said winding means so thatsaid cord may be wound or unwound by said winding means according to thedirection of rotation thereof; reversible drive means for said windingmeans; a plurality of pulleys of which at least one is mounted to saidsupport means and at least one is mounted to said arm; a parts holdercomprising a member having a surface to which said parts may be heldunder the influence of a magnetic field, a magnet capable of limitedmovement toward and away from said surface, and means biasing saidmagnet toward said magentic surface, and means connecting the oppositeend of said cord to said magnet so that said parts are suspended fromsaid cord and tension on said cord opposes said biasing means; aplurality of cord guiding means of which at least one is mounted to saidsupport means and at least one is mounted to said arm, said cordextending from said winding means to said magnet assembly along a pathdetermined by its engagement with said cord guiding means; stop means onsaid arm in position to be engaged by said parts holder member andthereby limit movement of said member toward said arm when said cord isbeing wound by said winding means; means for limiting swinging movementof said arm between first and second limit positions; said cord guidingmeans being disposed so that when said cord is under tension it exerts aturning force on said arm that urges said arm toward said second limitposition; and arm biasing means biasing said arm toward said first limitposition, said biasing means providing a turning force on said arm thatexceeds the turning force exerted by said cord when it is under tensionas long as said parts holder member is disengaged from said stop meansand is less than the turning force exerted by said cord when saidwinding means is operating to wind said cord with said parts holdermember in engagement with said stop means; said magnet biasing meansexerting a biasing force on said magnet which is greater than theturning force required to be exerted by said cord on said arm in orderto overcome the force exerted by said arm biasing means and move saidarm to said limit position, whereby said magnet cannot be pulled awayfrom said surface by said cord until said arm has been stopped in saidsecond limit position.
 2. A conveyor according to claim 1 furtherincluding: means for operating said drive means so as to sequentially(a) unwind said cord until it is slack due to said parts holder being inengagement with said parts to be lifted and transported, (b) stopunwinding and start winding said cord, (c) continue winding said cord sothat said arm is forced to swing to said second limit position and saidmagnet is caused to move away from said surface after said arm hasreached said second limit position, and (d) stop winding and startunwinding said cord so as to allow said magnet to move back to itsoriginal position with respect to said surface and thereafter allow saidarm to return to said first limit position.
 3. A conveyor according toclaim 1 wherein said arm biasing means comprises a second cord connectedto said arm, and means including a counterweight connected to saidsecond cord for causing said second cord to urge said arm toward saidfirst limit position.
 4. A conveyor according to claim 1 wherein saiddrive means is a reversible electric motor and said operating meanscomprises an electrical circuit for controlling operation of said motor,said circuit including limit switch means for stopping operation of saidmotor and additional switch means for reversing said motor.
 5. Aconveyor according to claim 4 wherein said circuit has two limitswitches and said additional switch means comprises two reversingswitches, and further including means for operating one limit and onereversing switch when said cord becomes slack and means for operatingthe other limit and reversing switches when a predetermined amount ofsaid cord has been wound by said winding means.
 6. A conveyor accordingto claim 5 further including another limit switch that is operated whensaid arm is swung to said second limit position.
 7. A conveyor accordingto claim 4 mounted so as to discharge parts into a hopper, and means forcontrolling operation of said drive means according to the supply ofparts in said hopper.
 8. A conveyor according to claim 7 wherein saidhopper is a bowl mounted on a vibrator, and said last mentioned meanscomprises a parts level sensor comprising a moveable member mounted soas to change position according to the level of parts in said bowl, anda switch that opens or closes according to the position of said moveablemember.
 9. A conveyor according to claim 7 wherein said hopper is partof an article counting machine.
 10. In combination with an articlecounting machine having a vibrating bowl feeder, a conveyor fordelivering parts to said bowl feeder, said conveyor comprising: an arm;means pivotally mounting said arm for swinging movement in asubstantially horizontal plane; a permanent magnet parts holderincluding a housing, a permanent magnet within said housing; and springmeans holding said magnet close to a surface of said housing; areversible cord winding mechanism; a flexible cord having one endconnected to said magnet and its opposite end connected to said windingmechanism; means on said arm for supporting said cord so that said partsholder is suspended from said arm by said cord; means for limitingswinging movement of said arm between a first parts loading position anda second parts releasing position above said bowl feeder; biasing meansfor applying to said arm a turning force that urges said arm to saidfirst parts loading position; cord guiding means arranged so that whensaid cord is under tension it applies to said arm a turning force thaturges said arm to said second parts releasing position; and stop meansfor stopping movement of said parts holder toward said arm when saidcord is being wound.
 11. A conveyor according to claim 10 furtherincluding: means for operating said winding mechanism so that said cordfirst lifts said parts holder until said parts holder is stopped by saidstop means, then pulls said arm to said second parts releasing position,next pulls said magnet away from said housing surface, then allows saidmagnet to move back to its original position with respect to saidhousing surface, next allows said arm to be pulled back to said firstparts loading position by said biasing means, and finally relowers saidparts holder.